RTM methods are methods for producing fibre composite components. RTM stands for Resin Transfer Moulding and describes the method activities. Such methods are in particular suitable for the production, on an industrial scale, of components with a low ratio of surface to volume. The method is suitable for producing high-grade components with a high fibre volume content, good reproducibility and little porosity.
There may be a need to create a tool for RTM methods, an RTM method, and a system comprising a tool for an RTM method, which all meet modern requirements.
According to an exemplary embodiment of the present invention the above-mentioned need may met by a tool for a resin transfer moulding method, which tool comprises a cavity, a resin trap and a transition region, wherein the cavity is adapted such that a component can be accommodated in it. Furthermore, the resin trap is integrated in the tool, and the transition region is designed such that with it a connection between the cavity and the resin trap can be established.
According to an exemplary embodiment a system for a resin transfer moulding method comprises a tool according to an exemplary embodiment of the invention, a pump and a storage container, wherein the pump is coupled to an output connection of the resin trap, and wherein the storage container is coupled to an input connection of the cavity.
According to an exemplary embodiment a resin transfer moulding method comprises the placement of a component in a cavity of a tool, feeding of resin in the cavity of the tool, and pressurisation of a resin trap that is integrated in the tool and communicates with the cavity. Preferably, the pressure is overpressure.
A basic idea of the invention may consist of a resin trap of a tool for a resin transfer moulding method (RTM method) being integrated in the tool. In other words the resin trap may be located in the tool itself. The resin trap may thus not be an external resin trap, as known from prior art, but instead an internal resin trap.
With the use of a tool according to the invention it may be possible to save an external resin connection, which according to prior art is required in order to couple the cavity of the tool to a resin trap. In this way any occurrence of sealing problems as a result of dirty seals is possibly reduced. Since there is no need to provide an external resin trap it may also be possible to do without other connection materials, such as for example hoses and hose clamps. These are frequently made as expendable or single-use components so that not having to provide these components possibly leads to savings in materials. Furthermore, it may be possible to do without cleaning of docking parts, for example hoses or clamps and other external parts, whether cleaning be carried out manually or automatically. Similarly, the consumption of resin is possibly reduced because the additional quantities of resin, required in RTM methods according to the state of the art, for example for filling inlet pipes, can be done without. As a result of the above-mentioned simplifications, the RTM method may overall be more cost-effective, efficient, able to be automated, and less prone to errors, which may lead to good method reliability.
By means of a tool according to the invention it may be possible to circumvent problems associated with prior art. In particular, it may be possible to avoid difficult docking of resin lines, which docking often resulted in sealing problems, e.g. as a result of resin-clogged lines, as a result of which in tools according to prior art a drop in method reliability may occur. Furthermore, with a tool according to the invention it may be possible to do without some external parts, which external parts usually cause additional cleaning expenditure.
Further objects, embodiments and advantages of the invention are shown in the secondary independent claims and in the dependent claims.
Below, exemplary embodiments of the tool for an RTM method are described in more detail, wherein designs that are described in the context of the tool for an RTM method equally apply to the system comprising a tool for an RTM method, and to the RTM method.
In another exemplary embodiment the tool further comprises a mould and a mould cover, wherein the mould and the mould cover are adapted such that when the mould and the mould cover are joined, the cavity and/or the resin trap and/or the transition region are/is formed.
The design of a tool in the embodiment of a mould and a mould cover may be a particularly efficient embodiment to form a cavity into which a component can easily be placed. In this arrangement the component can easily be placed in the cavity and, after the RTM method has been completed, can easily be removed from said cavity. Likewise, subsequent cleaning may be simplified by a two-part construction of the tool.
In a further exemplary embodiment the transition region comprises a separation element, wherein the separation element is arranged between the cavity and the resin trap and is adapted such that it at least partly engages the connection between the cavity and the resin trap in such a way that the connection between the cavity and the resin trap can be closed at least in part. Preferably, the separation element is adapted such that it forms a siphon-like transition region.
By providing a siphon-like transition region it may be possible to do without a method component, e.g. a shutoff cock, as is used according to prior art. By saving method components there may be savings in the costs of the component and of the connection and the cleaning of the shutoff cock. Furthermore, in this way the number of possible error sources may also be reduced.
In another exemplary embodiment the separation element is integrated in the mould cover and/or in the mould. In other words, the separation element may be integrated solely in the mould cover, solely in the mould (bottom part of the mould) or partly in the mould cover and partly in the mould.
Accommodating or integrating the separation element in the mould cover (top part of the tool) and/or in the mould, i.e. the bottom part of the mould, or in other words the bottom part of the tool may be a particularly efficient way of separating the cavity, at least in part, from the resin trap.
In a further exemplary embodiment the separation element is a shutoff cock.
Designing the separation element as a shutoff cock may be a particularly effective option for obtaining an interruption of the connection between the hollow space or cavity and the resin trap.
According to another exemplary embodiment the tool further comprises a control connection that is adapted such that the separation element is controllable by the control connection.
This embodiment may, in particular, be advantageous if the separation element is adapted as a shutoff cock. In this case, by providing a control connection, it may be possible for the shutoff cock to be efficiently controlled in the specified manner.
According to yet another exemplary embodiment of the invention the control connection is adapted such that electrical and/or pneumatic lines can be connected. Furthermore, the separation element can be adapted such that the separation element can be controlled electrically and/or pneumatically.
In a further exemplary embodiment the resin trap comprises an output connection, which output connection is preferably adapted such that it can be coupled to a pump.
Coupling the resin trap with a pump may be a particularly effective way of sucking resin into the cavity of the tool. Subsequently, if there is resin in the cavity and thus on/in a component located in the cavity, the pump can be used to pressurise the resin trap. Preferably the pump is a pump that can generate both negative pressure (vacuum) and positive pressure.
According to a further exemplary embodiment the cavity comprises an input connection. By this input connection it may be possible to feed resin into the cavity, for example by negative pressure and/or by positive pressure.
Below, exemplary embodiments of the system with a tool for an RTM method are described. The embodiments that are described in the context of the system also apply to the tool for RTM methods and to the RTM method.
In another exemplary embodiment the system further comprises a control unit that is designed such that it controls a pressure in the resin trap.
By providing a control unit that controls the pressure in the resin trap it may in a simple manner be possible to feed resin into the cavity of the tool, in that, for example, the resin trap is subjected to negative pressure. After the cavity has been filled with resin, the control unit may be operated such that it pressurises the resin trap, wherein such pressure may possibly render unnecessary a shutoff cock as is necessary in prior art. To this effect the control unit may possibly be controlled in such a way that the resin trap is subjected to counter pressure that prevents any further resin from the cavity from penetrating the resin trap.
In a further exemplary embodiment the control unit is adapted such that during a pressure dwell phase (Nachdruckphase) it keeps the resin level in the resin trap constant. Preferably, the control unit is furthermore adapted such that it maintains the pressure in the resin trap during a curing phase.
According to an alternative exemplary embodiment the system further comprises a control element, wherein the control element is adapted such that it controls the separation element. Preferably, in this arrangement the separation element is a shutoff cock which, for example, is pneumatically and/or electrically controllable by the control element.
Below, exemplary embodiments of the RTM method are described. The embodiments described in the context of the RTM method also apply to the tool for the RTM method, and to the system comprising a tool for an RTM method.
In another exemplary embodiment the RTM method furthermore involves increasing the pressure in the resin trap, wherein the increase takes place in a manner that the resin level in the resin trap remains constant.
Increasing the pressure in the resin trap may be an efficient way of preventing further resin from entering the resin trap from the cavity, as a result of which according to an exemplary embodiment of the invention it may be possible to do without a shutoff cock or another shutoff mechanism as is necessary according to prior art.
In a further exemplary embodiment the RTM method further involves maintaining the pressure in the resin trap during a curing phase.
A tool and/or a system according to an exemplary embodiment of the invention can for example be used for producing a component for an aircraft.
It should be pointed out that features or steps which have been described with reference to one of the above exemplary embodiments or with reference to one of the above aspects can also be used in combination with other features or steps of other exemplary embodiments or aspects described above.
One aspect of the invention may consists of a tool comprising an integrated resin trap. As a result of the integral arrangement of such a resin trap it may be possible to avoid connections and connection lines, as a result of which a design of a tool and/or a system for an RTM method may become possible, which design is simplified overall. Between a cavity and the integrated resin trap there may be a separation element that may be designed in the form of a shutoff cock or shutoff valve. By using a suitable geometric shape, for example by a large surface in relation to the volume of the tool or the cavity, it may also be possible to prevent any exothermal reaction that may occur under certain circumstances during curing of the resin, or it may be possible to at least lessen the effects of such an exothermal reaction. As an alternative the separation element may also form a siphon-like transition region that can be used as a shutoff mechanism if the pressure in the resin trap is controlled such that no further resin can enter the resin trap through the transition region. This may, for example, take place by applying overpressure.